There is no GMP requirement for lighting levels, other than “Production areas should be well lit” (EudraLex Vol 4, Part 1, §3.16) and “Adequate lighting shall be provided in all areas” (US CFR 21, 211.44)
NEBB procedural standards refers to IEST RP CC 006.3. It’s shown as an optional test. The Lux level is user defined but 500lux is the minimum recommended level in production environment. I’m not sure why you would want to “qualify” cleanrooms lighting levels if they are not a Critical Process Parameter (CPP).
There is a European Standard on “Lighting of indoor workplaces” (EN 12464-1, June 2011). It recommends a minimum of 500 lux for pharmaceutical production. Naturally the lighting can be less bright in corridors, changing rooms, storage areas and plant rooms.
The ISPE recommend 500lux minimum
Again there is no GMP standard - only that it needs to be sufficient. Also don’t qualify it, then if you change a light bulb, you don’t need to have a validation change control. It is a non-critical process parameter typically.